The invention relates to the field of rechargeable batteries comprising a plurality of electrochemical generators connected to each other in series and/or in parallel by a power line. The invention relates more particularly to the field of battery operation control systems.
A control system can monitor the charge and discharge status of the battery, as well as the temperature and/or the current in each electrochemical generator. Each electrochemical generator constitutes an independent module that can be discharged so that the battery supplies the electrical power required by a given application, for example an electric vehicle. Moreover, the battery can be recharged to increase the stored capacity in each electrochemical generator. A power line connects the generators to each other and ends in terminals designed for connection to the application.
The voltage measured at the terminals of a battery can be representative of the charge status of the electrochemical generators (or accumulators) that constitute the battery modules. The charge status of the electrochemical generators is thus subject to permanent monitoring by voltage monitoring devices. More particularly, these devices are designed to prevent the electrochemical generators experiencing overcharging or severe discharging, which reduce battery performance and especially limit battery life.
Documents EP A0678753, EP A0855780 and EP A1018652 describe systems and methods for controlling a set of electrochemical generators comprising a common logic and a plurality of measurement interfaces associated with each generator. The common logic is integrated into a master processor of the battery receiving the measurements coming from each generator interface acting as slave parts. The master processor controls one or more protection units according to the measurements supplied by the slave interfaces. The master processor represents a significant part of the cost of the battery control system. In fact, this master processor is generally specific to each type of battery (number and type of generators, operating parameters dependant on the target application, etc.). Moreover, the control systems described in the above-mentioned documents require complex and costly wiring. In EP A 1018652, a measurement interface is individually associated with each generator and a common logic is provided for the control system as a whole. The individual measurement interfaces provide their measurement signals successively by means of a first wired serial connection. The measurement signals are transmitted in response to interface selection pulses transmitted in series from one interface to the other by a second serial wired link. The quantity of measuring wires is particularly important and increases the risk of system malfunction.
Document WO A 2004/047215 proposes dispensing with the wiring required for the transmission of the measurements between the slave interfaces associated with each generator and the master processor, by transmitting these measurements via a wireless link, in particular via a radio link. This document however does not propose dispensing with the master processor. Furthermore, a radio link can be unreliable and if interference breaks the radio link, the system can be delayed in detecting abnormal operating conditions.
Moreover, document JP 11318033 describes a centralised management system for a battery. This document also proposes dispensing with the connecting wires required for transmission of the measurements between the slave interfaces associated with each generator and the master processor, by transmitting these measurements by connecting onto the power line. This document, however, does not propose dispensing with the master processor.
A need therefore exists for a simpler and cheaper battery control system, and in particular for a control system that allows for the master processor to be dispensed with, while reducing the connecting wires for the transmission of the parameter measurements for each generator.